Disc array apparatuses (also called as “RAID (redundant arrays of inexpensive disks) apparatuses”) have a configuration that enhances high-speed data access and data-failure resistance, and are used commonly as external storage apparatuses for use in information processing systems. The disk array apparatuses are often used in open systems that run on general-purpose operating systems of different types, and therefore have data formats of fixed-length records.
On the other hand, mainframe systems handle data formats of variable-length records. Thus, a storage control apparatus converts a data format of variable-length records into a data format of fixed-length records so as to allow access from a mainframe system to an external storage apparatus.
When storing data in the external storage apparatus, an error check code is added to the data such that a determination of whether there is an error is made upon reading the stored data again. For example, in CKD formats for mainframe systems, an error check code is added to each field of a record. In fixed-length data formats, an error check code is added to each logical block.
Please see, for example, Japanese Laid-open Patent Publications No. 2006-164141 and No. 2008-197804.
The storage control apparatus converts the data format of data received from a mainframe host, temporarily stores the data in its memory, and then stores the data in the external storage apparatus. The storage control apparatus may fail to write the data to the external storage apparatus due to an error occurring in the data. In this case, the storage control apparatus discards the erroneous data, transmits an error response to the mainframe host, and performs a host retry.
However, depending on the condition of the data error, the host retry may fail, leading to an error state in which the erroneous data is retained in the memory (for example, pinned data). In the case of such an error state, the data needs to be recovered by an engineer, which results in a recovery cost in terms of time, man-hours, expenses, and so on.
That is, by improving the performance of recovering from an error state, the recovery cost for the storage control apparatus may be reduced.